x86
reg ::= rsp | rbp | rsi | rdi | rax | .. | rdx | r8 | ... | r15
arg ::= $int | %reg | int(%reg)
instr ::= addq arg, arg |
subq arg, arg |
negq arg |
movq arg, arg |
callq label |
pushq arg |
popq arg |
retq
prog ::= .globl main
main: instr^{+}